once again I have a problem in SQL. I want to use a substring, which I otherwise used for a SELECT query, for a table UPDATE. The query looks like this:

SELECT SUBSTRING(h.action,LOCATE('"',h.action) 1,(((LENGTH(h.action))-LOCATE('"', REVERSE(h.action))-1)-LOCATE('"',h.action))) AS File, 
       h.TIMESTAMP, 
       h.user, 
       d.uid, 
       d.size 
       d.id 
from history h 
INNER JOIN data d ON h.contract = d.contract 
LEFT JOIN history ON d.user = history.user 
WHERE ( SELECT DISTINCT SUBSTRING(h.action,LOCATE('"',h.action) 1,(((LENGTH(h.action))-LOCATE('"', REVERSE(h.action))-1)-LOCATE('"',h.action)))) IN (SELECT filename FROM data) 
and h.contract=xy AND h.action LIKE 'file